Rudder



June 2, 1970 R; TAGGART 3,515,089

RUDDER Filed Sept. 30, 1968 3 Sheets-Sheet 1 R. TAGGART June 2, 1970 RUDDER 3 Sheets-Sheet 2 Filed Sept. 30, 1968 Ir PAP June 2, 1970 R. TAGGART 3,515,089

RUDDER Filed Sept. 50, 1968 3 Sheets-Sheet 5 Q9. 26 I /6 3 4770 NEKS United States Patent 3,515,089 RUDDER Robert 'I'aggart, Fairfax, Va., assignor to Robert Taggart Inc., Fairfax, Va., a corporation of Virginia Filed Sept. 30, 1968, Ser. No. 763,781 Int. Cl. B6311 25/38 US. Cl. 114--162 Claims ABSTRACT OF THE DISCLOSURE The present invention utilizes horizontally disposed foils rotatable about a horizontal axis or axes which foils utilize the propeller race to guide the vessel as well as bring about other substantial advantages. In the preferred embodiment disclosed herein, the foils rotate simultaneously in opposite directions so that both are raised or lowered together. The principles utilized may also be applied to other control surfaces on ships.

BACKGROUND OF THE PRESENT INVENTION Existing rudders for use on boats, ships and other vessels hereinafter referred to simply as vessels utilize one or more vertically positioned blades pivotal about a vertical or nearly vertical axis or axes. The plane defined by such a conventional rudder blade is, therefore, always in a generally vertical position. Although such rudders are, of course, widely used and accepted and produce satisfactory results, there exist certain disadvantages, limitations and other drawbacks in their use.

Such a rudder when rotated produces drag on the vessel as it moves through the water, thereby decreasing the net forward thrust applied to the hull by the propeller. Further, when a propeller is operating under dead pull or high slip conditions, the angularity of the rotational propeller race is greatly increased. Conventional rudders frequently stall under these conditions and provide little or no usable steering force but a large amount of drag.

Another disadvantage of the conventional rudder is discovered when the ship is turned. In a turn, the angle of attack of the conventional rudder increases rapidly as the rudder is first rotated, but then falls off as the angle of water flow past the rudder changes around the stern of the rotating vessel. This involves major variations in the torque required to turn and hold the rudder, as well as in the turning force and drag applied to the ship.

SUMMARY OF THE INVENTION The present inventionis directed to an improvement in control surfaces for vessels, and in particular, to improve rudders for such vessels.

This invention seeks to overcome the disadvantages listed above, as well as other disadvantages and to provide new and improved results by the utilization of horizontal- 1y disposed foils positioned in the propeller race. These foils are rotatable about horizontal axes or about a single horizontal axis, which on the preferred embodiment disclosed herein is concentric with the propeller axis. Also on the preferred embodiment disclosed, the foils are operated simultaneously and rotate in opposite directions whereby side or turning forces are created by the race on the foils. In addition, the surface of each foil that does not receive the primary contact from the propeller race is cambered.

The improved results obtained by this arrangement are manyfold. When the foils are in their neutral position (which is their horizontal position) there is no significant side or turning force applied to the rudder of the ship, as is often the case with a vertically positioned rudder. Any side force that is exerted on one foil, however, is balanced and offset by an equal and opposite force created on the 3,515,089 Patented June 2, 1970 opposite foil. A rotational moment is, however, applied to the foils by the propeller race, thereby creating a counter torque which opposes the torque applied to the ship by the propulsion machinery.

The camber of the foils creates a lift force which olfsets the drag produced by the foils and in fact, results in a net forward thrust applied to the hull. Due to the fact that the angle of attack of the foils to the propeller race does not change as the foils are raised or lowered, there is always present the maximum net forward thrust and the counter torque with the exception of a possible small reduction in each of these as the foils rotate due tothe offset of their axes. Where the axes of rotation for the foils are concentric with the propeller axis, even this slight change does not take place.

When raising or lowering the foils to effect a turn, the force exerted by the race opposing the moving of one foil is offset by an equal and opposite force urging the other foil in the direction of the desired movement. Accordingly, there is a balancing affect which results in only a small force needed to raise or lower the foils. Furthermore, the horizontal forces which are exerted on each of the foils and which provide the turning force for the ship are additive, thereby requiring less planform area to achieve the same side forces when compared to the conventional type rudder. In spite of the lower planform area required, control is maintained over the vessel when turning due to the fact that the angle of attack of the foils stays large despite the change in the flow angle of the water around the stern of the turning vessel.

It is, therefore, an object of the present invention to provide improved control surfaces for vessels, and in particular, improved rudders therefor.

Another object of the present invention is to provide an improved rudder utilizing horizontally disposed foils positioned in the propeller race to achieve beneficial results by means of utilization of the forces of the propeller race.

Yet another object is to provide such horizontally disposed foils pivotal about a common horizontal axis or adjacent horizontal axes and that move simultaneously and in opposite directions.

Still another object is to provide such an improved rudder assembly having cambered surfaces so that a net forward thrust is created on these foils by the propeller race.

Yet another object is to provide such an improved rudder assembly which will not appreciably lose its effective turning forces due to a change in the flow of water as the vessel moves through its turn.

An additional object of the present invention is to provide such a rudder assembly requiring less planform area than conventional rudders, yet which will provide substantially equal turning forces and which will require a relatively small amount of force applied in order to manipulate the foils.

Still another object of the present invention is to provide apparatus used to actuate and control the rudder foils.

Other and further objects, features and advantages will be apparent froman examination of the following description of a presently preferred embodiment of this invention which is given for the purpose of disclosure when taken in conjunction with the accompanying drawmgs.

BRIEF DESCRIPTION OF THE DRAWINGS Like character references designate like parts throughout the several views of the drawing, which views are as follolws:

FIG. 1 is a perspective view of the present invention as employed on a vessel having a right-hand propeller,

FIG. 2 is a side view of the apparatus shown in FIG. 1.

'FIG. 3 is a plan view of the apparatus of FIG. 1 as seen along section lines 3 -3 of FIG. 2.

FIG. 4 is a side view, in section, of a rudder foil as taken along section lines 4-4 of FIG. 3.

FIG. 5 is a side view, in section, of the other foil as viewed along section lines 5-5 of FIG. 3.

FIG. 6 is a rear view of the improved rudder, with the propeller and vessel not being shown for purposes of simplicity,

FIG. 7 is a partial side view, partially in section, of the support strut and actuating equipment for moving the rudder foils, and

FIG. 8 is a plan view, in section, of the apparatus shown in FIG. 7, as seen along section lines 8-8 of FIG. 7.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIGS. 1-3, there is shown the present invention as attached to the hull 10 of a ship in a preferred manner. The propeller in this embodiment is a right-hand propeller and is indicated by the numeral 12. The axis of rotation for the prope ler 12 is indicated by the numeral 14.

The rudder itself is carried by the support strut 16 and is comprised of two 'foils 18 and 20. Each foil in this preferred embodiment has two opposed surfaces, one surface 22 of each foil being essentially fiat, and the remaining surface 24 of each foil being cambered. For a righthand propeller such as we have disclosed in this preferred embodiment, the foil 18 has its cambered surface as its lower surface and the foil has its cambered surface as its upper surface. This is more clearly shown by the section views of FIGS. 4 and 5.

The foils are rotatably mounted on the support 16.

For optimum results, their axes of rotation should coincide with the axis of rotation 14 of the propeller 12. When viewed from the top as in FIG. 3, the foil axes of rotation do not coincide with that of the propeller due to the fact that separate hinge means are employed in this embodiment. These hinge means will be more fully discussed below, but for the present, it will be suflicient state that the foils are rotatable abouts shafts carried by housings 26 which extend laterally from either side of the support strut 16.

The forces created to turn the ship are achieved by rotating either both foils to a raised position, which will give a port or left turn with a righthand propeller, or to a lowered position, which will give a starboard turn with a righthand propeller. These positions are illustrated from a rear view in FIG. 6, with the up position being indicated by the letter A and the down positions by the letter B. We will now move into a discussion of the basic operation of the foils disclosing how the forces are created and the results they bring about.

The rudder is positioned within the propeller race coming from the propeller 12 which can be seen by an examination of FIGS. 1-3. The race coming from the propeller will, of course, move in a spiral or rotative fashion. Since the propeller shown in the drawings is a righthand propeller, its race will rotate in a clock-Wise direction when viewed from the rear of the rudder. Accordingly, the races primary contact will be with the surface 22 of the foils 18 and 20. The race will move generally in the direction of the arrows 27 with respect to the foil 18.

In discussing the forces exerted on the foils, reference should be made to FIGS. 2 and 6, which figures carry arrows representative of some of these forces.

One obvious effect that the race will have on the foils when they are in their neutral or horizontal position will be the vertical forces indicated by the arrows 28 in FIG. 6. Thus, a torque is set up in the rudder, and this will oppose an opposite torque established in the vessel by the propulsion machinery.

A not so obvious effect created by the race is the lift that develops in the rudder to offset its drag. These forces are illustrated by the arrows in FIG. 2. Because of the cambered surface 24 of the foil 18; the water flow around this lower surface 24 will increase and thin out relative to the water flow on the top surface 22, thereby creating the forward lift force indicated by the arrow 30. The drag produced by the rudder structure is illustrated by the arrow 32. When these forces are added together, the resultant force is represented by the arrow 34 giving a net forward thrust illustrated by the arrow 36. The vertical component 28 of the foil lift force acts downwardly on the starboard foil 18 and upwardly on the port foil 20 (see FIG. 6), but with the net result being a forward thrust produced at each foil.

Accordingly, rather than produce a drag on the movement of the vessel, and thereby decrease its net forward thrust, the rudder of the present invention actually creates a forward thrust, thereby giving optimum propeller thrust augmentation when the foils are in their neutral positions. It should also be pointed out that when the foils are raised or lowered to their turning positions, their angle of attack to the propeller race does not appreciably change. Accordingly, the flow about the cambered surface continues essentially the same as when the foils are in their neutral position. Thus, the net force acting on each foil does not change appreciably in either magnitude or direction relative to the foil. For this reason, the torque and forward lift thrust applied to the ship through the support strut remain substantially unchanged as the foils pivot. Furthermore, as the foils are simultaneously raised or lowered, the vertical components 28 counterbalance each other, one opposing the motion and one assisting it. Accordingly, and by appropriately linking the foils together, only a small force is required to move the foils as will be discussed more fully be ow.

Assuming now that one wishes to make a starboard or right turn, the foils are lowered to their lower position shown in FIG. 6. Remembering that the propeller race moves in a spiral fashion with the rotation being in a clock-wise direction as viewed in FIG. 6, in our example the side forces of the race will contact the foils moving generally in the direction of the arrows 38 of FIG. 6. The horizontal components of the forces 38 are indicated by the arrows 40. These horizontal forces are additive, thus producing the net horizontal or turning force represented by the arrow 42. Thus by lowering both foils, forces are exerted by the propeller race against the foils in a port direction, causing the ship to make a starboard turn.

To achieve a port turn, both foils are raised to their positions indicated by A on FIG. 6. As with the downward position, the side force of the propeller race strikes the surfaces 22 of the foils creating a force thereon represented in direction and magnitude by the arrows 44. The net horizontal components are represented by the arrows 46. The arrow 48 indicates the direction and magnitude of the net additive turning force created on the raised foils and moving to the starboard side of the ship. The result is a turn to the port side.

As will be readily understood by one skilled in the art, the horizontal component of any force exerted on foils in their raised or lowered positions will increase the further the foils are moved from their horizontal position. Thus if a slow, gradual turn is desired, the foils will be rotated only a small amount from their horizontal or neutral position, and if a sharp turn is desired, the foils will be rotated to their maximum limits.

Mathematically, the horizontal side or turning force created is equal in magnitude to the sum of the forces perpendicular to the foils multiplied by the sine of the angle to which they are raised or lowered. Because of the interference at the hinge areas, this angle may be limited to approximately 60 to 70 degrees. This is satisfactory, however, because these angles will give about 90% of the total force available for steering purposes. Calculations on a large single screw cargo ship indicates that side forces equal to those developed by the existing, conventional rudder can be obtained with a rudder of the present design having only 60% of the planform area of the conventional rudder. Accordingly, a decrease in cost and amount of materials used can be realized.

This new concept of rudder design involves the adaptation of the hydrofoil section shape (as seen in FIGS. 4 and 5), angle of attack of the rudder section and the area distribution to the velocity characteristics of the propeller race in which it is to work. These must be obtained either by calculation or by model tests. The sizing of the foils and the thickness distribution is dictated by strength factors, as is the sizing of the support strut. For large ships, for example, the strength must be sufiicient to withstand the additional forces imposed by the ships rolling and pitching. The foils, however, also have the desirable feature in this situation of opposing these unwanted motions.

One disadvantage of conventional rudders pointed out previously is that when operating under dead pull or high slip conditions, the angularity of the rotational race is greatly increased, causing conventional rudders to fre-- quently stall and provide little or no usable steering force, yet create a large amount of drag. The rudder described herein will develop maximum side forces under such conditions with little increase in drag, and thus, are ideal for towing vessels and for low speed maneuvering. Further, when going into a turn the angle of attack of conventional rudders increases rapidly and then falls off as the flow angle changes around the stern of the vessel. This results in major variations in the torque required to turn and hold the rudder and then the side force and drag which the rudder applies to the ship. The rudder of the present invention is by contrast little affected by the ship rotation except at the maximum angles.

The particular type of support used to rotatably mount the foils 18 and 20 may, of course, vary, By way of example, a hinge nacelle may be supported either aft of the rudder or through an extension of a hollow propeller shaft. One arrangement that would prove satisfactory is the support strut 16 shown in the drawings. This support strut has been sized to house the raising and lowering machinery which is more clearly shown in FIGS. 7 and 8. As with the particular type of support, the apparatus used to raise or lower the foils may also vary and the invention disclosed herein is not intended to be limited by either the type of support means or the type of actuating equipment used except when specifically claimed.

Turning now to FIGS. 7 and 8 this particular embodiment of actuating machinery will now be discussed. This embodiment utilizes hydraulically actuated rack and pinion means cooperating with spur gears on the shafts with which the foils rotate.

Turning now to FIG. 7, a master control cylinder 50 carries a piston 52 slidable therein and actuated by the control piston rod 54. The hydraulic accumulator vessels 56 are connected to the control cylinder 50 on opposite sides of the piston 52 for vibration damping. These accumulators receive compressed air by means of the conduit 58 and contain actuating hydraulic fluid 60.

Turning now to the mechanical means utilized to simultaneously rotate the foils, it is comprised primarily of a rack 62, cylinders 64 and 66 positioned at opposite ends of the rack and pinion gears 70. These cylinders 64 and 66 are connected by means of lines 68 to the master cylinder 50 on opposite sides of the piston 52. Portions 65 and 67 of the rack 62 are received within the cylinders 64 and 66, respectively, and act as piston means within these cylinders.

Referring now to FIG. 8, it can be seen that the pinion gears 70 are connected by means of idler gears 72 to spur gears 74 and 76. The spur gears'74 are fixed to shafts 78 to which the foil 18 is keyed for rotation with these shafts 78. In like manner, the spur gears 76 are connected to shafts to which the foil 20 is fixedly attached. Appropriate seal means are provided about each of the shafts 78 and 80, as well as the shafts on which the pinion gears 70 are mounted.

Turning now to the operation of this apparatus, and assuming that the foils are in their neutral positions and that one desires to make a right turn, control means in the vessel are actuated causing the control piston rod 54 to move to the right as viewed in FIG. 7. This forces hydraulic fluid into the cylinder 64 and out of the cylinder 66. This movement of the hydraulic fluid results in the rack being moved downwardly, causing the pinion gears 70 to rotate in an inboard direction. In like manner, the idler gears 72 will also rotate in an inboard direction causing the spur gears 76 and 78 to rotate in an outboard direction. The result is a lowering of the foils 18 and 20. This lowering of the foils will bring about turning forces 40 (see FIG. 6) resulting in a starboard or right turn. A left or port turn is, of course, achieved in the same manner except that the control rod 54 and piston 52 are moved to the left as viewed in FIG. 7.

One advantage of the simultaneous action of the rudder foils disclosed herein is that a minimum amount of force or torque is required to rotate them about their axes. Because the foils are geared or linked together so that they rotate through equal angles in opposite directions, the hydrodynamic forces opposing and assisting the raising and/or lowering are equal and opposite so that they can be balanced by the gearing or by linkages. Thus, the primary need for power to operate the rudder is that required to overcome the friction in the mechanical elements. The forces exerted on the foils may not remain exactly equal, especially as the foils near their maximum raised and lowered positions. This is due to the fact that greater force can be exerted by the race on the foil 20 in the raised position and the foil 18 in the lowered position. The reason for this is that one foil and the support strut may partially block the other foil in the respective positions named in the last sentence.

As can be seen, therefore, the present invention achieves the objectives set forth at the outset. An improved rudder has been disclosed which will not only provide economy in its manufacture, simplicity in its assembly and use, but also more reliable and efiicient con trol over the steering of a vessel. A rudder has been disclosed which makes use of the rotational flow of the propeller race to provide a more controllable steering side force per unit of foil area with no reduction in the net forward thrust applied to the hull. It allows optimum propeller thrust augmentation in its neutral position with little or no degradation of thrust augmentation when in one of its many steering positions. The rudder also provides for a partial balance of the torque applied to the hull by the propulsion machinery, as well as provides improved anti-rolling and anti-pitching features. A minimum force or torque is required for the actuation of the present invention, and there is developed a minimum variation in control forces and forces applied to the hull when a ship moves into a turn. In addition to this, it provides improved performance when the propeller is operating under high slip conditions. Finally, the actuation and movement of the rudder foils disclosed herein may be performed with simplified steering machinery.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for the purpose of disclosure, numerous changes in the detail of construction and the combination, shape, size and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. An improved rudder for a vessel having a propeller for driving the vessel comprising,

two foils positioned in the propeller race and rotatable along at least one generally horizontal axis, said foils extending outwardly from said axis on opposite sides thereof, said axis extending generally toward the propeller, and

means for rotating the foils in opposite directions of rotation.

2. The invention of claim 1 wherein the propeller race moves in a generally spiral path, and wherein,

each of the foils has opposed surfaces, the propeller race primarily contacting one surface of each foil, and the other of said surfaces of each foil being cambered.

3. The invention of claim 1 or 2 wherein said rotating means is further defined as means for simultaneously rotating the foils in opposite directions.

4. The invention of claim 3 and including,

a support fixed to the vessel, and

shaft means for each of the foils rotatably mounted in said support, each of the foils being rotatable with its respective shaft means.

5. The invention of claim 4 wherein said rotating means is further defined as spur gears on said shafts for rotation therewith,

pinion gears operatively connected to the spur gears,

a rack movably positioned between the pinion gears,

and

control means for controlling the movement of the rack.

6. The invention of claim 5 wherein said control means is further defined as,

hydraulic cylinders positioned about opposite end portions of the rack and in sealing engagement with said end portions, each having an inlet and an outlet for the flow of actuating fluid, and

master cylinder means for selectively directing actuating fluid to and from said hydraulic cylinders.

7. An improved rudder for a vessel having a propeller which rotates in afirst direction of rotation comprising,

a support fixed to the vessel,

two foils extending outwardly from said support on opposite sides thereof and being rotatable on said support about generally horizontal axes, said foils being positioned in the propeller race, and

means for simultaneously rotating said foils in opposite directions of rotation.

8. The invention of claim 7 wherein,

the propeller race moves in a generally spiral path of travel, and

the foils are positioned on opposite sides of the two axes, each having opposed surfaces, said spirally moving race primarily contacting only one of said surfaces on each foil, the other of said surfaces on each foil being cambered.

9. The invention of claim 8 wherein said rotating means is further defined as including,

shaft means on each foil rotatable in said support and defining the axis for its foil,

pinion gears operatively connected to each of the shaft means for the rotation thereof,

a rack positioned between, and in contact with said pinion gears for the rotation thereof, and

means for controlling movement of the rack.

10. An improved rudder for a vessel having a propeller which rotates in a first direction of rotation comprising,

a support fixed to said vessel,

two foils rotatably connected to said support about parallel and adjacent axis means, and extending outwardly on opposite sides of said axis means,

spur gears connected to the axis means for rotation therewith,

two pinion gears operatively connected to the spur gears for rotation thereof,

a rack disposed between and in contact with said pinion gears for rotation thereof in opposite rotational directions, and

means for selectively moving the rack.

References Cited UNITED STATES PATENTS 2,705,469 4/1955 Kohnenkamp 114-162 XR ANDREW H. FARRELL, Primary Examiner 

